Apparatus of this type have long been known from the prior art. In this case, plastics material pre-forms are usually first heated and are then expanded to form plastics material containers by means of a shaping device, such as in particular a blow-moulding device. In many applications it is necessary for sterilization of the plastics material containers to be carried out, in particular in the case of sensitive beverages such as for example fruit juices or milk or even in the case of medicines.
It is customary in the prior art for sterilization of the finished blow-moulded containers to be carried out, in which case an inner wall of these containers in particular is sterilized. The drawback of this sterilization of the containers is that they already have a relatively large surface and a large quantity of sterilization agent, such as for example hydrogen peroxide gas, is therefore necessary.
In the prior art a switch from sterilizing the plastics material containers to sterilizing the plastics material pre-forms has therefore started in part, since the latter have a considerably smaller internal surface than the finished blow-moulded containers.
A method and an apparatus for producing sterile packaging containers is known from EP 1 086 019 B1. In this case a suitable method comprises first a pre-heating stage in which the expansible material is heated to an internal surface temperature which exceeds a dew point temperature of a gaseous sterilizing active material but which is below the glazing temperature of the thermoplastic material. In addition, a sterilization stage is provided, in which the sterilizing active material is introduced into the gas phase, as well as a final heating stage, in which the blank is heated to a temperature above the glazing temperature of the blank. In this case therefore the sterilization procedure takes place inside a heating device which heats the pre-forms so that they can subsequently be shaped out by means of blasting air. In this way the temperature of a heating device can be used at the same time to facilitate the sterilization process. On the other hand there is also the drawback, however, that the heating device in question can be permanently damaged by the sterilization agent, such as for example hydrogen peroxide.
A method of producing a sterile container starting from a pre-form is known from EP 0 996 530 B1. In this case a sterilizing product which is capable of being activated by heat is applied to a pre-form and the pre-form is heated in order to activate the sterilizing product at the same time. With this process too there is the drawback, however, that the sterilization is carried out in a heating device which per se is used for the pre-heating of the pre-forms and which can therefore be attacked by the frequently highly corrosive gas.
In addition, various apparatus which sterilize the containers without using gaseous media, for example using electron beams or UV light, are known from the prior art. Apparatus of this type, however, frequently require a very precise screening so that the beams which are very dangerous in part cannot pass to the outside.
It may be desirable therefore to make available an apparatus for producing plastics material containers which permits an inexpensive and efficient sterilization of the containers.